My first prolog program!

main.pl

distance(A, B, Dist) :-
	A = (X1, Y1),
	B = (X2, Y2),
	Dx is X2 - X1,
	Dy is Y2 - Y1,
	Dist is sqrt(Dx * Dx + Dy * Dy).

closest([X | Xs], Target, Min) :-
	distance(X, Target, Dist),
	closest_ext(Xs, Target, (X, Dist), Min).

closest_ext([], _, (Min, _), Min).
closest_ext([Candidate | Xs], Target, Current, Min) :-
	Current = (_, CurrentDist),
	distance(Candidate, Target, CandidateDist),
	(CurrentDist < CandidateDist -> Next = Current ; Next = (Candidate, CandidateDist)),
	closest_ext(Xs, Target, Next, Min).

main :-
	Points = [(0, 0), (1, 1)],
	closest(Points, (0, 1), Min),
	write(Min), nl,
	halt.

makefile

all:
	@swipl -o main.out -g main -c main.pl 2> /dev/null

run: all
	@./main.out